In recent years, as an example of a sensor substrate, in the medical and pharmaceutical fields (e.g., drug development, clinical diagnosis), array substrates have been used for various analyses such as gene analysis, Single Nucleotide Polymorphism (SNPs) analysis, or an analysis of the interaction between substances.
An array substrate is mainly used for a bio-array substrate. The array substrate includes plural sensor substrates having regions including reaction fields in which an interaction occurs. The sensor substrates are arranged in an array. Target substances are fixed to respective reaction fields and then sample solution is dripped thereon. As a result, the interaction between the detection substance and the target substance contained in the sample is promoted. Then, the interaction level can be detected based on the fluorescence intensity and can be used for an analysis.
In order to improve the sensitivity at which the substance is detected, the sensor substrate is required to increase the interaction strength in the reaction field in which the interaction with the detection substance occurs. On the other hand, in order to form a reaction field on the sensor substrate, a method has been widely used in which a probe substance selectively coupled to the detection substance is absorbed in the surface of the sensor substrate. In order to increase the interaction strength in the reaction field, it is required to increase the amount of the probe substance absorbed in the surface of the sensor substrate (i.e., to increase the amount of the probe per unit area). However, there is a limit on the amount of the probe that can be absorbed per unit area. In another method, the interaction strength is increased by increasing the surface area of the sensor substrate. For example, the surface of the sensor substrate functioning as a reaction field is caused to be rough and porous. Alternatively, the surface area can be increased by adhering porous material, such as agarose, nitrocellulose or glass fiber, to the sensor substrate. By these methods, the sensor substrate can have an increased surface area to increase the absorbed amount of the probe substance, thus increasing the interaction strength in the reaction field.
In conventional sensor substrate, however, a spot diameter within which liquid permeates may be undesirably expanded or droplets may be repelled. Accordingly, an accurate analysis may be difficult, thus resulting in declined detection accuracy.